1,1,2,2-Ethenetetrathiolate (ett⁴⁻) coordination polymers, such as poly[K_x(Ni-ett)], have been known for decades for their excellent thermoelectric properties. However in reality, ett⁴⁻ is neither a “true” comonomer which participates in the polymerization, nor represents a “true” repeat unit of the target polymer. Indeed, poly[K₂(Ni-ett)], which is formally the product of Ni-induced polymerization of ett⁴⁻, has a poor conductivity and needs to be oxidized to show attractive thermoelectric characteristics. The polymerization and oxidation processes are poorly controllable which causes irreproducibility of the polymer properties. To improve the synthesis reproducibility, we studied polymerization of potassium tetrathiooxalate (K₂tto), the convenient synthesis of which was developed in our recent work. Because K₂tto is the “true monomer”, and not its precursor, a high quality product is reproducibly formed simply by mixing K₂tto with NiCl₂ at room temperature. The procedure does not require additional components (bases), or special conditions (prolonged heating), which are usually needed for the preparation of this polymer from the monomer precursor 1,3,4,6-tetrathiapentalene-2,5-dione (TPD). Furthermore, as tto²⁻ is formally the product of two-electron oxidation of ett⁴⁻, the poorly controllable oxidation process is avoided and poly[Ni-tto] almost free from K is directly formed upon the complexation of Ni²⁺ and tto²⁻. Thus-obtained poly[Ni-tto] possesses conductivity in the range of 27–47 S cm⁻¹ and a Seebeck coefficient in the range of −38 to −55 μV K⁻¹, which are superior thermoelectric properties compared to poly[K_x(Ni-ett)] samples obtained by the previously reported methods. Redox and structural properties of poly[Ni-tto] were compared with those of poly[K_x(Ni-ett)] obtained by the reported methods. Furthermore, DFT calculations were performed to shed more light on generally promising properties of this class of materials. Particularly, possible packing models have been predicted for polymers, and the molecular dynamics simulations have been used to simulate the molecular arrangements under ambient conditions.

A Pd/Pt‐Bu₃ catalyst having bulky, electron‐rich ligands significantly outperforms conventional “step‐growth catalysts” Pd(PPh₃)₄ and Pd(Po‐Tol₃)₃ in the Suzuki polycondensation of the AB‐type arylene‐based monomers, such as some of the substituted fluorenes, carbazoles, and phenylenes. In the AA+BB polycondensation, Pd/Pt‐Bu₃ also performs better under homogeneous reaction conditions, in combination with the organic base Et₄NOH. The superior performance of Pd/Pt‐Bu₃ is discussed in terms of its higher reactivity in the oxidative addition step and inherent advantages of the intramolecular catalyst transfer, which is a key step joining catalytic cycles of the AB‐polycondensation. These findings are applied to the synthesis of a carbazole‐based copolymer designed for the use as a hole conductor in solution‐processed organic light‐emitting diodes.

Laser sintering as a thermal post treatment method for dispenser printed p- and n-type bismuth telluride based thermoelectric paste materials was investigated. A high-power fiber laser (600 W, 1064 nm) was used in combination with a scanning system to achieve high processing speed. A Design of Experiment (DoE) approach was used to identify the most relevant processing parameters. Printed layers were laser treated with different process parameters and the achieved sheet resistance, electrical conductivity, and Seebeck coefficient are compared to tube furnace processed reference specimen. For p-type material, electrical conductivity of 22 S/cm was achieved, compared to 15 S/cm in tube furnace process. For n-type material, conductivity achieved by laser process was much lower (7 S/cm) compared to 88 S/cm in furnace process. Also, Seebeck coefficient decreases during laser processing (40–70 µV/K and −110 µV/K) compared to the oven process (251 µV/K and −142 µV/K) for p- and n-type material. DoE did not yet deliver a set of optimum processing parameters, but supports doubts about the applicability of area specific laser energy density as a single parameter to optimize laser sintering process.